Rock drill steel grinders



Oct 15, 1957 B. v. NYHOLM 2,809,470

ROCK DRILL STEEL GRINDERS Filed May 9, 1955 2 Sheets-Sheet 1 Fig/ 5 ATTORNEY Oct. 15, 1957 B. v. NYHOLM 2,809,470

ROCK DRILL STEEL GRINDERS Filed May 9, 1955 2 Sheets-Sheet 2 Fig.5

65 64 811/ m +--rr- 12:: ll f l W I: 63 i" I I I! ATTGRNEY United States Patent ROCK mans. STEEL GRINDERS Bengt Viktor Nyholm, Saltsjo-Boo, Sweden, assignor to Atlas Copco Aktie'nclag, Nacka, Sweden, :1 corporation of Sweden Application May 9, 1955, Serial No. 597,037

Claims. (Cl. 51-32) This invention relates to rock drill steel grinders, and particularly to grinders for sharpening chisel type rock drill bits. One object of the invention is to provide a simple and rigid grinder which may be operated by nonskilled workers, and in which the peripheral surface of a cylindrical grinding wheel is worn very evenly. A still further object of the invention is to provide a grinder of this type which is cheap in manufacture and in which all parts are of simple and rugged design to withstand handling by unskilled Workers. A still further object is to provide a grinder which may also be used for other grinding purposes during which the grinding wheel is not reciprocated axially. For these and other purposes I provide a rock drill steel grinder comprising a substructure, a device for releasably securing a drill steel in fixed position, a carrier mounted to swing on said substructure on a swinging axis, said swinging axis being an axis of a surface of revolution including the cutting end face of said drill steel, means for mounting a rotary grinding wheel on said carrier so as to grind along said surface, means for rotating said grinding wheel on an axis of rotation parallel to said swinging axis, and means for imparting to said grinding wheel a reciprocating movement in the direction of said swinging axis.

In the accompanying drawings two embodiments of rock drill steel grinders incorporating the invention are illustrated by way of example, it being understood, however, that these embodiments are by no means limiting of the invention which may be varied in several difierent ways within the scope of the claims. Fig. l is a plan view of a rock drill steel grinder according to the invention, and Fig. 2 is a side view of the grinder according to Fig. 1 looking towards the grinding wheel. Fig. 3 is a section on line IHIII in Fig. 1 and Fig. 4 is a section on line IVIV in Fig. 1. Fig. 5 is a plan view of a part of the grinder according to Fig. l in a modified form.

The rock drill steel grinders illustrated in the drawings are intended for grinding the cutting end faces of rock drill steels having chisel type bits. The grinder illustrated in Figs. 1-4 consists of a substructure 1 which may be bolted to a bench or casing 2 by means of bolts 3. The substructure 1 forms two brackets 4, 5 for bearings 6, 7 for a shaft 8. A'carrier is provided on the shaft 8 and comprises a first member 9 secured to the shaft 8 by means of bolts 10 and a second member 11 forming a slide which slides on guides 12 on the first member 9 perpendicularly to the shaft 8. The second member 11 in Fig. 1 forms a housing 13 for bearings (not illustrated) in which a shaft 14 of a grinding wheel 15 is mounted for rotation. A guard plate 16 is mounted on the housing 13 to protect the operator of the grinder. The grinding wheel is held on the shaft 14 by a nut 17 and a disc 18 in conventional manner. A flexible shaft 19 is connected to the shaft 14 of the grinding wheel for driving the same by means of a suitable coupling (not illustrated).

In order to make possible adjustment of the distance between the swinging axis of the carrier 9, 11 and the axis of rotation of the grinding wheel 15 a screw 20 is rotatable in a bore in a lug 21 on the first carrier member 9 by means of a wheel 22 fixed on the end of the screw 20. The screw 20 is threaded in a bore in a lug 23 formed on the carrier member 11 and an annular abutment 24 is fixed on the screw 20 for cooperation with the lug 21. Furthermore, a helical spring 25 is fitted on thescrew between the lug 21 and the wheel 22. Obviously, by rotating the wheel 22 the lug 23 and the carrier member 11 may be movedon the carrier member 9 longitudinally of the guides 12. In any position of adjustment the carrier member 11 is locked against displacement towards the shaft 8 but the spring 25 permits a certain displacement of the member 11 away from the shaft 8.

For releasably securing a rock drill steel 26 to the grinder a bracket 27 is formed by the substructure 1, said bracket carrying a slide 28 which may be adjusted by means of a wheel 29 and an adjustment screw 30 locked against axial displacement in the slide 28 and screw threaded in the bracket 27. A support 31 is swingably mounted on the slide 28 on a bolt 32 said support being provided with an arcuate opening 33 for a bolt 34 serving to lock the support 31 in selected positions on the slide 28. A lever 35 swingable on a pin 36 mounted in spring fittings 37 secured on the support 31 is provided with a grooved eccentric 38 serving to press the drill steel 26 on to the support 31. A finger 39 is formed by the support 31 and serves to limit forward movement of the drill steel towards the grinding wheel. The support 31 forms two bed portions 40 and 41 onto which the drill steel is pressed by the eccentric 38 when the lever 35 is moved from a forward or upright position into the position illustrated in Figs. 1 and 2.

In order to produce reciprocation of the grinding wheel 15 and the shaft 8 in the longitudinal direction of the shaft 8 one end portion 44 of said shaft 8 is mounted in a sleeve 43 which is rotatable in the bearing 7. The portion 44 of the shaft 8 disposed in the sleeve 43 is provided with a circumferential continuous helical groove 45 forming cam surfaces cooperating with a pin 46 fitted in a corresponding opening in the sleeve 43. Couplings are provided for connecting the shaft to the sleeve 43 and the sleeve 43 to the bearing 7. Said couplings consist of rollers 48, 49 mounted in recesses 50, 51 formed in the enlarged end portion of the sleeve 43. The recesses 50, 51 taper in the direction of the arrow 52. In operation of the grinder the shaft portion 44 is oscillated as indicated by the arrow 53. Springs 54 and 55, respectively, serve to urge the rollers 48, 49 into engaging positions. When the shaft 8, 44 is turned in the direction of the arrow 52, Fig. 4, the roller 48 is moved into engaging position so that the shaft portion 44 is coupled to the sleeve 43 and turns the sleeve, whereas roller 49 is disengaged. When the shaft is turned in the opposite direction to arrow 52 the roller 49 is engaged and holds the sleeve 43 in fixed position relative to the bearing 7 whereas the roller 48 is disengaged so that the shaft can turn freely in the sleeve 43.

In operation the grinder according to the invention described hereinabove operates in the following manner:

When drill steel is to be ground the steel is placed on the bed portions 44 41 with one end face 69 against the finger 39, with the cutting edge 61 in a vertical plane, and the other end face 62 presented to the grinding wheel. The lever 35 is swung down from a forward or upright position in which the cam 38 permits the insertion of the steel to the horizontal position illustrated in Figs. 1 and 2 inwhich the cam 38 secures the steel by pressing it against the bed portions 40, 41. The motor (not illustrated) or other device which drives the shaft 1 is started and rotates the grinding wheel. The wheel 22 is then turned until the rotating grinding wheel is in contact with the end face 62. i The operator now holds the housing 13 withone hand and moves it up and down thereby swinging the grinding wheel and the shaft 8 so that the whole of the end face 62 is ground. Simultaneously, the operator turns the wheel 22 thereby feeding the grinding wheel towards the drill steel until a sufficient amount of t. e drill. steel has been ground away. During the swinging up and down the shaft 8 with its portion 44 alternately entrain-s and'releases the sleeve 43 which is alternately released from and coupled to the bearing sleeve 7 and is caused to move "intermittently in the direction of the arrow 52 in Fig. 4. The intermittent rotation of the sleeve 43 causes the pin 46 to move along the groove 45 thereby imparting to the shaft 3 a slow reciprocating movement in the'direction of the swinging axis so that the grinding wheel 15 moves from the position illustrated in full lines in Fig. 1 to the position illustrated in chain dotted lines, and vice versa.

The spring 25 prevents the grinding wheel from being pressed too hard against the cutting face 62 and thereby prevents burning of the steel.

The wheel 22 and screw 29 may be used to adjust the distance between the swinging axis of the carrier 9, 11 and the axis of rotation of the grinding wheel to take up for the wear of the grinding wheel. The screw 29 may be used to move the slide .28 for the same purpose. Said slide and screw may sometimes be dispensed with.

The angle between the end faces 61') and 62 may be varied at wilt by loosening the screw 34 and adjusting the support 31 on the slide 28 and then tightening the screw 34 in a new position. The support 31 may sometimes be made integral with the bracket 27 or slide 28 when it is not deemed necessary to provide facilities for adjustment of the angle between the end faces of the drfll steel.

The grinder above described and illustrated on the drawings should be considered only as an example and various modifications may be made within the scope of the claims. Instead of providing the groove 45 in the shaft 8 the groove may be provided in the sleeve 43 and a pin corresponding to the pin 46 in the shaft 8. When it is desired to use an electric or compressed air driven standard grinding machine the modification of Fig. 5 may be used. The grinding machine 63 which is controlled by an operating lever 64 (switch or air supply control) is mounted in a clamp 65 formed by the end portion of a modified carrier member 11 which fits the carrier member 9 in the same way as in the embodiment of Figs. 1 and 2.

Whatl claim is:

l. A rock driii steel grinder comprising a substructure, a device for releasably securing a drill steel in fixed posi tion, a carrier mounted to swing on said substructure on a swinging axis, said swinging axis being an axis of a surface of revolution including the cutting end face of said drill steel, means for mounting a rotary grinding wheel on said carrier so as to grind along said surface, means for rotatin said grinding wheel on an axis of rotation parallel to said swinging axis, and means for imparting to said grinding wheel 'a reciprocating movement in the direction of said swinging axis upon swinging of said carrier on the swinging axis. 7

2. A rock drill steel grinder according to claim 1, in

which the carrier consists of a first member mounted on a shaft for swinging on the swinging axis, and a second member carrying the grinding wheel and formed as a slide slidable on said first member in a direction perpendicular to said swinging axis.

3. A rock drill steel grinder according to claim 2, in which a screw carrying a hand wheel is screw threaded in a lug on said second carrier member, said first carrier member having a lug with a bore through which the screw extends freely, an abutment fixed on the screw and cooperating with said lug on the first carrier member to form an adjustable non-yielding stop for relative motion of the carrier members to reduce the distance between the axis of rotation and the swinging axis, and a spring interposed between said hand wheel and the lug on the first carrier member to form a yieldable stop permitting a certain extension of the carrier members in various selected positions of adjustment and limiting the grinding pressure of the grinding wheel to a value defined by the tension of the spring.

4. A rock drill steel grinder comprising a substructure, a device for releasably securing a drill steel in fixed position, a carrier mounted on a shaft to swing on said sub structure on a swinging axis, said swinging am's being an axis of a surface of revolution including the cutting end face of said drill steel, means for mounting a rotary grinding wheel on said carrier so as to grindalong said surface, a rotatable sleeve mounted on a portion of said shaft rotatable on the shaft and in the substructure but locked against axial displacement inthe substructure, a continuous circumferential screw line cam surface and a cam follower cooperating therewith provided one on said shaft portion and the other on said sleeve in cooperative positions to produce axial reciprocation of said shaft upon rotation of the sleeve relative to the shaft, and couplings between said sleeve and said substructure and between said shaft and the sleeve causing said shaft to entrain the sleeve and the sleeve to be disengaged from the substructure upon turning of the shaft in one direction and upon turning of the shaft in the opposite direction to release the shaft fromthe sleeve and to hold the sleeve relative to the substructure. v

5. A rock drill steel grinder according to claim 3, in which each one of said couplings comprises a roller movable in a runway tapering in one direction and urged in said direction by a spring.

6. A rock drill steel grinder comprising a substructure, a device for releasably securing a drill steel in fixed position, a carrier mounted to swing on said substructure on a swinging axis, said swinging axis being an axis of a surface of revolution including the cutting end face of said drill steel, means for mounting a rotary grinding wheel on said carrier so as to grind along said surface, and means for imparting to said carrier a reciprocating movement in the direction of said swinging axis upon swinging of the carrier on the swinging axis only.

References Cited in the file of this patent UNITED STATES PATENTS 1,774,508 Fowler Sept. 2, 1930 2,137,140 Lewis Nov. 15, 1938 FOREIGN PATENTS 702,293 Great Britain Jan. 13, 1954 

